Influence of anti-oestrogens on gonadotrophin secretion in control and ACTH-infused immature rats

1984 ◽  
Vol 105 (3) ◽  
pp. 308-313 ◽  
Author(s):  
David R. Mann ◽  
Michael S. Blank ◽  
R. Sridaran ◽  
V. Daniel Castracane ◽  
Charles Eldridge ◽  
...  
Keyword(s):  
Serum Testosterone ◽  
Serum Levels ◽  
Inhibitory Effect ◽  
Female Rats ◽  
Constant Infusion ◽  
Simultaneous Treatment ◽  
Serum Lh ◽  
Gonadotrophin Secretion ◽  
Immature Rats ◽  
Lh Secretion

Abstract. The objective of this study was to determine whether anti-oestrogens (nafoxidine, MER-25) would block the suppressive effects of ACTH on gonadotrophin secretion in immature rats. Female rats were castrated at 25–26 days of age, and an Alzet osmotic minipump containing ACTH (1–24) or saline was implanted in each animal. ACTH was administered at a rate of 1 IU/day by constant infusion. Beginning on the day of surgery, animals were injected daily for 5 days with 0.25, 5 or 25 μg/100 g body weight of nafoxidine or 5 mg MER-25 and sacrificed on the sixth day following castration. ACTH lowered serum LH concentrations and increased pituitary LH levels. Serum androstenedione concentrations were more than two times greater in ACTH-infused than in control rats, but serum oestrone levels were not affected. Serum testosterone and oestradiol concentrations in ACTH-infused rats remained below levels of detection. Administration of 0.25 μg of nafoxidine prevented the suppressive effects of ACTH on serum LH. Serum levels of LH in these animals were comparable to saline-treated controls (418 ± 94 vs 443 ± 73 ng/ml). The two higher doses of nafoxidine and MER-25 were ineffective in suppressing the actions of ACTH on serum LH. MER-25 reduced serum LH values in both controls and ACTH-infused rats. Serum FSH concentrations were not altered by ACTH or nafoxidine treatment. MER-25 elevated pituitary FSH concentrations in both control and ACTH-infused rats. These data suggest that the inhibitory effect of ACTH on LH secretion in immature rats is mediated by an oestrogenic steroid, since this action can be blocked by simultaneous treatment with a low dose of the anti-oestrogen, nafoxidine.

Cholinergic inputs to the amygdala and the control of gonadotrophin release

1980 ◽  
Vol 93 (1) ◽  
pp. 1-6 ◽  
Author(s):  
Flavio Piva ◽  
José Borrell ◽  
Patrizia Limonta ◽  
Gilberto Gavazzi ◽  
Luciano Martini
Keyword(s):  
Nicotinic Receptors ◽  
Serum Levels ◽  
Inhibitory Effect ◽  
Female Rats ◽  
Muscarinic Agonist ◽  
Time Intervals ◽  
Gonadotrophin Secretion ◽  
Lh Release ◽  
Lh Secretion ◽  
Cholinomimetic Drugs

Abstract. Adult female rats castrated 4 weeks before were implanted bilaterally into the basomedial area of the amygdala with drugs known to mimic or to counteract the actions of acetylcholine. The animals were sacrificed at different time intervals after the implantation of the different compounds, and serum levels of LH and FSH were measured by radioimmunoasay. The data obtained indicate that the intra-amygdalar implantation of the muscarinic blocker atropine induces a significant increase of the release of LH without altering FSH secretion. The implantation of two cholinomimetic drugs, pilocarpine, an almost pure muscarinic agonist, and carbachol, which possesses both muscarinic and nicotinic properties, exerted an inhibitory effect only on LH release. On the contrary, the intra-amygdalar placement of the nicotinic blocker mecamylamine was followed by an increase of FSH with no changes in LH. These observations may suggest that cholinergic signals reaching the amygdala may be of some relevance in the mechanisms controlling gonadotrophin secretion. Muscarinic receptors seem to play an inhibitory role in the regulation of LH secretion, while nicotinic receptors seem to modulate in an inhibitory way FSH release.

A comparison of the effects of gonadal steroids on naloxone-induced LH secretion in gonadectomized rats

1986 ◽  
Vol 110 (2) ◽  
pp. 327-334 ◽  
Author(s):  
G. M. Spencer ◽  
S. A. Whitehead
Keyword(s):  
Inhibitory Effect ◽  
Gonadal Steroids ◽  
Ovariectomized Rats ◽  
Endogenous Opioid ◽  
Feedback Effects ◽  
Serum Lh ◽  
Gonadotrophin Secretion ◽  
Endogenous Opioid Systems ◽  
Hypothalamic Pituitary Axis ◽  
Lh Secretion

ABSTRACT The effects of the opiate antagonist naloxone on serum LH concentrations was investigated in gonadectomized rats given different regimes of steroid pretreatment. Two injections of testosterone given 48 and 24 h before naloxone treatment failed to reinstate LH responses to this drug in castrated rats while subcutaneous testosterone-filled silicone elastomer capsules implanted for a week were effective in this respect. Injections of oestrogen, oestrogen plus progesterone or progesterone alone all restored LH responses to naloxone in ovariectomized rats when given 48 and/or 24 h before drug treatment, although the magnitude of these responses varied according to the precise steroid treatments. The hypothalamic-pituitary axis was also responsive to naloxone just before the progesterone-induced LH surge in oestrogen-primed ovariectomized rats. Results show that gonadal steroids are permissive to the effects of opiate drugs, but they suggest that endogenous opioid systems do not necessarily mediate the negative feedback effects of steroids. Some other factor(s), as yet unidentified in the rat, may control the opioid modulation of gonadotrophin secretion or exert an independent inhibitory effect on gonadotrophin release. J. Endocr. (1986) 110, 327–334

Effect of sulpiride-induced hyperprolactinaemia on catecholamine turnover and LRH concentration in the medial basal hypothalamus of rats

1983 ◽  
Vol 102 (3) ◽  
pp. 321-326 ◽  
Author(s):  
Fumio Chatani ◽  
Toshihiro Aono ◽  
Koji Koike ◽  
Keiichi Tasaka ◽  
Keiichi Kurachi
Keyword(s):  
High Performance Liquid Chromatography ◽  
High Performance ◽  
Serum Levels ◽  
Female Rats ◽  
Monoamine Oxidase Inhibition ◽  
Medial Basal Hypothalamus ◽  
Catecholamine Turnover ◽  
Serum Lh ◽  
Oxidase Inhibition ◽  
Lh Secretion

Abstract. In order to clarify the mechanism of hyperprolactinaemic anovulation, the medial basal hypothalamic (MBH) catecholamine (CA) turnover and LRH concentration, and the serum levels and pituitary contents of gonadotrophins and prolactin (Prl) in hyperprolactinaemic female rats were examined. Hyperprolactinaemia (HPrl) was produced by oral administration of sulpiride for 10 consecutive days; each measurement made on the sulpiride-treated rats was compared with that of control dioestrus rats. Prl, LH, FSH and LRH were determined by radioimmunoassay; CA turnover, as assessed by the accumulation of CA following monoamine oxidase inhibition, was assayed by high performance liquid chromatography with electrochemical detection. Sulpiride treatment induced (1) an increase in the serum Prl and a decrease in the serum LH, (2) an increase in the pituitary FSH and LH contents, (3) an increase in the MBH LRH concentration, and (4) an increase in the MBH dopamine (DA) turnover. These results suggest that HPrl may induce anovulation by impaired LH secretion which was caused by the suppression of LRH release due to an increase in DA turnover in the MBH.

A GONADOTROPHIN-RESPONSIVE VIRILIZING ADRENAL TUMOUR IDENTIFIED AS A MIXED GANGLIONEUROMA AND ADRENOCORTICAL ADENOMA

1978 ◽  
Vol 89 (4) ◽  
pp. 701-709 ◽  
Author(s):  
Hisatoshi Takahashi ◽  
Kenichi Yoshizaki ◽  
Hideyuki Kato ◽  
Toshihisa Masuda ◽  
Goro Matsuka ◽  
...  
Keyword(s):  
Serum Testosterone ◽  
Serum Levels ◽  
High Serum ◽  
Normal Serum ◽  
Constant Infusion ◽  
Normal Female ◽  
Adrenocortical Adenoma ◽  
Serum Lh ◽  
The Right ◽  
Lh Rh

ABSTRACT A 38-year-old gravida 2, para 1 woman, who had suffered from virilization and amenorrhoea for 8 years was examined. She had peripheral serum testosterone (T) levels of 3.9–8.7 ng/ml (normal level: 0.32 ± 0.09 ng/ml) with normal serum levels of dehydroepiandrosterone (DHA), aldosterone and cortisol (F) and normal urinary 17-ketosteroids (17-KS). Dexamethasone (DXM 2 mg/day for 5 days) suppressed the serum F level adequately, but reduced the high T levels only slightly. The administration of commercial hCG 6000 IU for 3 days increased both the serum T levels (5.68 to 9.83 ng/ml) and the serum DHA levels (4.9 to 9.8 ng/ml, normal range 4–6 ng/ml), but synthetic ACTH-Z (Cortrosyn-Z®, 1 mg, Organon) did not affect the serum T level. The basal serum LH level was abnormally low, and constant infusion of synthetic LH-RH (200 μg/5 h) resulted in good responses of serum LH and FSH and increase in the serum T level from 5.2 to 9.1 ng/ml. Computerized tomography, ultrasonography and pneumo-retroperitoneumroentgenography showed the presence of a large tumour in the right adrenal. The tumour was a circumscribed irregularly lobulate mass, measuring 16×8×8 cm and weighing 500 g. Histologically, it was identified as a ganglioneuroma containing numerous scattered groups of large polyhydral cells similar to adrenocortical cells, forming islets in some places. After removal of the tumour from the right adrenal, the high serum T level decreased to the normal female level in 24 h.

Effects of the new prolactin-producing tumour 7315b on gonadotrophin secretion in adult male and female rats

1989 ◽  
Vol 120 (2) ◽  
pp. 261-268 ◽  
Author(s):  
A. Kooy ◽  
R. F. A. Weber ◽  
M. P. Ooms ◽  
J. T. M. Vreeburg
Keyword(s):  
Serum Levels ◽  
Female Rats ◽  
Male Rats ◽  
Suitable Model ◽  
Intact Male ◽  
Adult Rats ◽  
Male And Female ◽  
Male And Female Rats ◽  
Serum Lh ◽  
Gonadotrophin Secretion

ABSTRACT The effects of the transplantable purely prolactin-secreting tumour 7315b on serum gonadotrophins were studied in adult rats. Possible contributions of the adrenals to the tumour-induced inhibition of serum LH and FSH were evaluated. The suppressive actions of tumour 7315b on serum gonadotrophins in gonadectomized plus adrenalectomized male and female rats were compared. Within 4 weeks after inoculation of tumour 7315b in intact male rats very high levels of prolactin and decreased serum levels of gonadotrophins and testosterone were recorded. At autopsy reduced weights of testes and accessory sex organs and slightly increased adrenal weights were found. In addition, in animals treated with a small testosterone-filled capsule after castration, tumour 7315b reduced serum concentrations of LH and FSH. Adrenalectomy did not prevent this suppressive action of the tumour on the post-castration rise of serum gonadotrophins. Suppression of serum gonadotrophins during hyperprolactinaemia was greater in gonadectomized plus adrenalectomized female rats than in male rats, indicating that the degree of the tumour-induced suppression of LH and FSH after castration is determined to a large extent by the sex of the animal. The purely prolactin-secreting tumour 7315b has therefore been shown to be a suitable model for studying the effects of severe hyperprolactinaemia on the pituitary-gonadal axis in rats. Journal of Endocrinology (1989) 120, 261–268

ADRENERGIC INPUTS TO THE AMYGDALA AND THE CONTROL OF GONADOTROPHIN RELEASE

1979 ◽  
Vol 90 (3) ◽  
pp. 385-393 ◽  
Author(s):  
José Borrell ◽  
Flavio Piva ◽  
Luciano Martini
Keyword(s):  
Brain Stem ◽  
Dopamine Receptor ◽  
Serum Levels ◽  
Female Rats ◽  
Receptor Blocker ◽  
Dopaminergic Drug ◽  
Gonadotrophin Secretion ◽  
Biphasic Effect ◽  
Adrenergic Blocker ◽  
The Brain

ABSTRACT Drugs able to mimic or to antagonize the action of catecholamines have been implanted bilaterally into the basomedial region of the amygdala of adult castrated female rats. The animals were killed at different intervals after the implantation of the different drugs, and serum levels of LH and FSH were measured by radioimmunoassay. The results have shown that the intra-amygdalar implantation of the alpha-adrenergic blocker phenoxybenzamine induces a significant increase of the release both of LH and FSH. The implantation of the beta-adrenergic blocker propranolol brings about a rise of LH only. The dopamine receptor blocker pimozide stimulates the release of LH and exerts a biphasic effect (stimulation followed by inhibition) of FSH secretion. The alpha-receptor stimulant clonidine and the dopaminergic drug 2-Br-alpha-ergocryptine were without significant effects. From these observations it is suggested that the adrenergic signals reaching the basomedial area of the amygdala (possibly from the brain stem) may be involved in the modulation of gonadotrophin secretion.

ENDOCRINE STUDIES AND SUCCESSFUL TREATMENT IN A PATIENT WITH TRUE HERMAPHRODITISM

1979 ◽  
Vol 91 (1) ◽  
pp. 184-192
Author(s):  
Evangelina Valdés ◽  
Carlos Fernández del Castillo ◽  
Raul Gutiérrez ◽  
Fernando Larrea ◽  
Martha Medina ◽  
...  
Keyword(s):  
Chromosome Complement ◽  
Reproductive Function ◽  
External Genitalia ◽  
Serum Testosterone ◽  
Serum Levels ◽  
Normal Children ◽  
Serum Lh ◽  
Genital Ambiguity ◽  
And Gender ◽  
Lh Rh

ABSTRACT A 12-year old, 46 XX true hermaphrodite born with genital ambiguity was studied and successfully treated. The serum LH and FSH profile resembled that of a pubertal normal individual, and LH-RH administration induced a normal LH response. Baseline testosterone serum levels were within the range for normal children. Exogenous HCG stimulation induced a significant serum testosterone increase up to values similar to those observed in normal post-pubertal males. Surgical examination disclosed the presence of bilateral ovotestis, normal Mullerian derivatives, epididymis, and vas deferens. A complete ovotestis with testicular predominance and the testicular portion of the contralateral ovotestis as well as the Wolffian derivatives, were removed. A further HCG stimulation 3 months after surgery, failed to induce serum testosterone increase. Spontaneous menarche was observed 6 months after surgery and ovulation was well documented. At present the patient has several characteristics of female sex including those of chromosome complement, gonad, internal and external genitalia, hormone levels and gender identity, thus demonstrating that treatment was successful and that reproductive function could be obtained. The finding of spontaneous ovulation following removal of the testicular portion suggests normal cyclic gonadotrophic release implying a difference between animal models and man in regard to hypothalamic virilization.

Non-responsiveness of serum gonadotropins and testosterone to pulsatile GnRH in hemochromatosis suggesting a pituitary defect

1993 ◽  
Vol 128 (4) ◽  
pp. 351-354 ◽  
Author(s):  
Lise Duranteau ◽  
Philippe Chanson ◽  
Joelle Blumberg-Tick ◽  
Guy Thomas ◽  
Sylvie Brailly ◽  
...  
Keyword(s):  
Single Pulse ◽  
Serum Testosterone ◽  
Pulse Amplitude ◽  
Pulse Frequency ◽  
Gonadotropin Secretion ◽  
Pulsatile Gnrh ◽  
Serum Lh ◽  
Before And After ◽  
Gnrh Therapy ◽  
Lh Secretion

We investigated the potential pituitary origin of gonadal insufficiency in hemochromatosis. Gonadotropin secretion was studied in seven patients with hemochromatosis and hypogonadism, before and after chronic pulsatile GnRH therapy. Pulsatile LH secretion was studied before (sampling every 10 min for 6 h) and after 15-30 days of chronic pulsatile GnRH therapy (10-12 μg per pulse). Prior to GnRH therapy, all the patients had low serum testosterone, FSH and LH levels. LH secretion was non-pulsatile in four patients, while a single pulse was detected in the remaining three. Chronic pulsatile GnRH administration did not increase serum testosterone levels; similarly, serum LH levels remained low: neither pulse frequency nor pulse amplitude was modified. We conclude that hypogonadism in hemochromatosis is due to pituitary lesions.

EFFECTS OF MATING AND INJECTION OF LUTEINIZING HORMONE RELEASING HORMONE ON SERUM LUTEINIZING HORMONE AND TESTOSTERONE CONCENTRATIONS IN RABBITS

1978 ◽  
Vol 76 (3) ◽  
pp. 417-425 ◽  
Author(s):  
C. A. BLAKE ◽  
PATRICIA K. BLAKE ◽  
NANCY K. THORNEYCROFT ◽  
I. H. THORNEYCROFT
Keyword(s):  
Luteinizing Hormone ◽  
Serum Testosterone ◽  
Serum Levels ◽  
Transient Increase ◽  
Marked Rise ◽  
Luteinizing Hormone Releasing Hormone ◽  
Releasing Hormone ◽  
Serum Lh ◽  
Before And After ◽  
Lh Rh

The effects of coitus and injection of luteinizing hormone releasing hormone (LH-RH) on serum concentrations of LH, testosterone and dihydrotestosterone (17β-hydroxy-5α-androstan-3-one; DHT) were tested in male rabbits. Before experimentation, male and female rabbits were housed in individual cages in the same room. Male rabbits were then bled by cardiac puncture before and after placement with female rabbits or intravenous injection of LH-RH. Serum LH, testosterone and DHT were measured by radioimmunoassay. Sexual excitement (sniffing, chasing and mounting), with or without intromission, caused a marked rise in serum testosterone and DHT concentrations in only some of the bucks. These increases were accompanied or preceded by a small, transient increase in serum LH. In the rest of the bucks, sexual excitement with or without intromission had either no effect on serum levels of all three hormones, or only serum testosterone and DHT decreased during the collection period. Similar responses were measured in bucks which were housed in a room without does for 2–4 weeks before experimentation. Injection of 10, 30 or 100 ng or 50 μg LH-RH caused serum LH, testosterone and DHT to rise in all bucks tested, but the magnitude of the rises in serum testosterone and DHT were not related to the magnitude of the LH rise. In both mated and LH-RH-injected bucks, the rises in serum testosterone and DHT were greatest in animals with low initial testosterone and DHT values. Under the conditions of this study, the data suggest that: (1) serum testosterone and DHT rise in only some male rabbits after sexual excitement (with or without intromission), (2) the rises in serum testosterone and DHT are dependent on a small transient increase in serum LH and (3) sexual excitement is less likely to cause release of LH-RH in bucks with raised serum testosterone and DHT concentrations.

The role of oestrogens on gonadotrophin secretion in the testicular feminization syndrome1

1980 ◽  
Vol 95 (3) ◽  
pp. 314-318 ◽  
Author(s):  
Martha Medina ◽  
Alfredo Ulloa-Aguirre ◽  
Maria A. Fernández ◽  
Gregorio Pérez-palacios
Keyword(s):  
Clomiphene Citrate ◽  
Poor Response ◽  
Testicular Feminization ◽  
Normal Response ◽  
Serum Lh ◽  
Gonadotrophin Secretion ◽  
Before And After ◽  
Complete Form ◽  
Lh Secretion

Abstract. The role of oestrogens on gonadotrophin secretion was assessed in three related patients with the complete form of testicular feminization syndrome. Serum LH and FSH levels were measured before and after I.RH stimulation as well as before, during and after chronic clomiphene citrate administration. Moderately elevated LH basal levels with a significant LH rise following I.RH were observed. Normal or even low FSH level with poor response to LRH were found in all subjects. Administration of clomiphene citrate resulted in a significant serum LH increase without any change of FSH. Following castration both LH and FSH rose and a normal response to LRH was observed. These results were interpreted as demonstrating that, while endogenous oestrogens modulate LH secretion in patients with androgen unresponsiveness, it plays no role in regulating FSH secretion and suggested that a factor of testicular origin without androgenic or oestrogenic activity is responsible for FSH regulation.

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